Mechanical fastener systems, such as bolt and nut fasteners, are commonly used to connect components of a structure together. However, in many structures, access to the fastener system is limited to only one side (e.g., the exterior) of the structure. In response to this problem, the nut may be fixed in its fastened position prior to installation and tightening of the bolt.
Further, the effects of vibration and thermal expansion transmitted to the fastener system can lead to loosening of the fastener system (e.g., the bolt counter-rotating and loosening itself from the nut). The effects from vibrations and thermal expansion on fastener systems may be particularly problematic in the aerospace industry. In response to this problem, the fastener system also includes a wire attached to the bolt, where the tension in the wire prevents the bolt from rotating. However, these anti-rotation devices can negatively impact the aerodynamics of the outer surface of the structure, which may be particularly problematic in the aerospace industry. There is therefore a need for a mechanical fastener system having an anti-rotational feature that minimizes the effect on the aerodynamic efficiency of the exterior surface of a structure.
Moreover, in many applications, particularly in the aerospace industry, the exterior of the structure may be exposed to or experience very high temperatures. As examples, the exterior surfaces of atmospheric reentry vehicles, hypersonic vehicles and internal jet engine exhaust components may get extremely hot during operation. In response to this problem, the exterior surfaces of the structure are typically covered with a Thermal Protection System (TPS) such as ceramic tiles, panels, blankets, ceramic matrix composites or actively cooled liners. Such thermal coverings are typically bonded to the surface of the structure, for example, over any fasteners used to connect the structure, with high temperature adhesives. However, removal of these thermal coverings for repair or replacement is labor intensive and costly. There is therefore a need for a mechanical fastener system to mechanically attach thermal coverings and that is capable of withstanding high temperatures.
Accordingly, those skilled in the art continue with research and development efforts in the field of fastener systems.